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Carps Great Lakes debut spawns action in Sault and across gov’ts

In this file photo, Asian carp, jolted by an electric current from a research boat, jump from the Illinois River near Havana, Ill. The U.S. Army Corps of Engineers released a draft report earlier this year outlining US $275 million in new defences to prevent the fish from reaching the Great Lakes. Among proposals are underwater noise and powerful water jets.

Asian carps have arrived in the Great Lakes but so far haven’t established reproducing populations.

Government and agencies in Canada and the United States have put priority on preventing them from doing so.

Lauren Tonelli, Asian carp project manager at the Invasive Species Centre, based in Sault Ste. Marie, said four species of carp concern local and international researchers: bighead, silver, grass, and black.

“All four of these species are native to China and southern Russia, but were brought to North America for use in aquaculture,” Tonelli told Sault This Week.

Marc Gaden, communications director at the Great Lakes Fishery Commission, a binational research and control agency, explained how the carp went from their use in aquaculture to North American waterways.

“Back in the 70s, it was actually kind of de rigueur to find natural, environmentally friendly ways to control things like algae and reeds and stuff like that, so these fish were raised in fish hatcheries down in the deep southern United States to keep their aquaculture tanks clean,” Gaden said, comparing the practice to that of fish hobbyists tossing a sucker into a fish tank to help keep it clean.

He pointed out the fish would often end up sold in Asian food markets.

“Well, where do you place a fish farm,” Gaden continued. “You place it next to a river, because you need lots of water.”

When the rivers then overflow, as often happens, the fish farms become inundated with water and the carp are allowed to escape into the public waterways, he said.

The carp thrived in the Mississippi River system and kept moving northward, as a result of these escapes.

Gaden added, grass carp are often kept in ponds, in subdivisions or golf courses for example, to keep them free of unwanted vegetation, but only in sterile form. Researchers believe that many of the live-caught grass carp are escapees or releases of these fish.

Despite some captures of live carp, both Tonelli and Gaden emphasize that so far, none of the four carp species have become established in the Great Lakes.

“Only three bighead carp were found, all in western Lake Erie, between 2000 and 2003, and are believed to have been intentionally released,” said Tonelli.

“Of the grass carp specimens, there have been approximately 23 single captures since 2012 in the waters or tributaries of Lake Huron, Lake Ontario, and Lake Erie.”

Tonelli pointed out “There is no evidence that there is a breeding population” of grass carp within the Great Lakes, but added, researchers have recently found evidence of natural reproduction of the species in the Sandusky River.

To keep a close eye on carp populations and potential breeding in Canada, “Fisheries and Oceans Canada has an extensive monitoring program that searches specifically for Asian carps to ensure that they are aware of any potential individual that may be in Canadian waters,” Tonelli said

Although some might believe a few fish found here and there in bodies of water as big as the Great Lakes shouldn’t be of major concern, Gaden, who works from the commission’s secretariat in Ann Arbor, Mich., quashes this idea.

“As few as 10 males and 10 females in a river system could be enough to establish a population,” he said, referencing the findings of a binational carp risk assessment headed by Fisheries and Oceans Canada.

“So in other words, efforts at prevention need to be basically at 100 per cent. You can’t just let a few in.”

An established population would have major implications for the local ecosystem, he said.

“Silver and bighead carp can eat up to 20 per cent of their body weight in phytoplankton and zooplankton, which make up the basis for the aquatic food web,” he said.

“Grass carp consume large quantities of aquatic vegetation which can destroy wetlands, increase water murkiness, and reduce spawning and cover habitats for native fishes.

“Black carp could destroy the native mollusk population in the Great lakes and in turn cause a decrease in native species that rely on mollusks as their main food source, such as the lake sturgeon, which is a species at risk.”

In other words, “They’re basically pulling the rug out from the bottom of the foodweb,” Gaden said.

This puts many native fish species at risk, and in turn will decrease commercial and recreational fishing opportunities, impacting jobs and revenues, as well as impacting avian habitat and populations, such as ducks.

Tonelli said Asian carp is a threat the federal government takes very seriously.

“The Canadian government has spent $17.5 million over the past five years to prevent and detect Asian carps in the Great Lakes.

“In the 2017 federal budget, $43.8 million was given to Fisheries and Oceans Canada to combat aquatic invasive species, a portion of which will be for Asian carp response and control,” said Tonelli.

Efforts are being made in the U.S. to prevent the carp from making their way from the Mississippi River into the Great Lakes as well.

Gaden explained, much of the reason the carp could make it from the southern U.S. into the Great Lakes in the first place was the destruction of a natural barrier at the Chicago River in the late 19th century, so the United States Army Corps of Engineers is looking into ways to close off that pathway again.

However, the cost for that will run in the billions of dollars, said Gaden, so the funding for that project has not been committed.

Despite the challenges, both Tonelli and Gaden are happy with the level of co-operation between all the organizations involved in Asian carp control and are optimistic for the future.

“With the recommitment of the federal government to fund aquatic invasive species, we expect that there will be continued prevention, response, and control of Asian carps in the Great Lakes,” said Tonelli.

“We hope Canada, the provinces, and our U.S. partners will continue to work together to help protect the Great Lakes from all aquatic invasive species.”